maybe two years if you are in the process of regenerating nerves. but if the underlying cause isnt found and treated, or in many cases even if it is treated, the nerves will continue to deteriorate. this is why it is important in my opinion to get tested thoroughly and quickly. you have a small window of opportunity to recover substantially in most cases. after that the damage may have progressed past the point of being able to recover. that is not to say you cant reach a state of equilibrium as well where you wont recover completely but may recover partially or not progress further.